7mm Mag Max Powder w/ H4831SC 154 gr Hornady SST

[Fursty]

Just starting reloading. Looking for accurate load for longer distance (400-600 yds) Shooting 154gr Hornady SST in Hornady brass. Here are results of working up load so far. My fps are lower than Hornady and Hodgdon for the same gr powder. I would like to get to 2900 fps if the consistency I am seeing continues, but that projects out at just over 65 gr. From book, Hornady and Hodgdon is at 61/62 gr. for their max.


Hornady Book (154 gr.)
gr. Velocity
56.3 --- 2600
58.6 --- 2700
61 ---- 2800

Hodgdon Book (150gr.)
gr. Velocity
59 --- 2775
62 --- 2986

Here is my data so far. No signs of overpressure yet.

GR. Avg fps
57 ---- 2571
57.5 --- 2602
58 ---- 2624
58.5 --- 2637
59 ---- 2652
59.5 --- 2671
60 ---- 2697
60.5 --- 2711

GR. fps Extreme Spread
57 ---- 28
57.5 --- 16
58 ---- 17
58.5 --- 9
59 ---- 3
59.5 --- 10
60 ---- 4
60.5 --- 14



What are the Gr./Expected fps from other books like Lyman for a 150 or 154 gr 7 mm?

Fursty

 

[Captcurt]

The 6th Edition Nosler Manual has the max of 65 gr of H4831 SC and a velocity of 3075 fps. They used a Wiseman 24" barrel and a 150gr bullet. My Lyman book is loaned out.

 

[jmr40]

You may have to try another powder to get the speeds you want. I know speed isn't everything, but why have a 7 mag if you are shooting 100 fps slower than 280 speeds. I've owned a couple of 7 mags in the past, sold the last one after I started loading and bought a chronograph. The big 7 looks good on paper, but I really had to work hard to find loads that would beat 30-06 or 270 speeds with similar bullet weights.

I found similar results, speeds were quite a bit slower than the loading manuals suggested I should have been getting. I can easily get 3050 fps from my 30-06 with 150's and 2950 isn't that hard with 150's from a 270.

A lot of people report good success with Reloder 22, I finally got the speed I was looking for with Reloder 25 in mine. But by then I'd found a rifle in 300 WSM that I liked better and the 7 became expendable. If you can get the advertised speeds the 7mag is a good choice though.

 

[Fursty]

Thanks for the info.

When looking at consistency/accuracy how important is the extreme spread on the velocity?

 

[GooseGestapo]

Speer #14 gives max of 62.0gr for 2,853fps. (160gr bullet).
This correlates closely with what you're seeing. Hodgdon data is usually a bit optimistic with the large magnums, and they're using 26" or longer barrels.

Indeed, I understand your pain. What you're seeing is why I don't own a 7mmMag.
I made the "mistake" of chronographing my 7mm08 with some factory ammo. I'd intended to build it into a .284,or 6.5-284 or even re-chamber to 7mmWSM as a gunsmith offered at a reasonable price. I declined...

I get 2,900+fps from 139gr Hornady's, and 2,800fps from 150's (RL17). And that from a 20"bbl !

Western "Magnum" and RL25 will give you best speeds and MagPro may be worth a try. I've actually seen those and RL33 and others while Varget and RL15 are nowhere to be found...

Back in the '80's when I was loading for friends 7mag's H4831 was the slowest around and to get "published" speeds from a 24" bbl we had to lean hard on the powder scales and accept sticky extraction and flattened and cratered primers. That was just what it took to get "magnum" performance.

Today there are too many powder choices, especially on the "slow" end of the Spectrum.
I also suggest you check out Jeff Bartlett's web site www.gi-brass.com
The WC-870, and WC-872 are just what you need and prices are "right".
I've used WC-860 I got in '05 with excellent results from my .300RUM and .257wby with satisfaction. (3,300fps from .300 w/180gr and 3,200fps w/120gr from the .257wby. and excellent accuracy).
Use the Winchester LR Magnum primer or Fed 215 and a near full case will give you what you're look for.
If that doesn't work, re-chamber to 7mmSTW and start over with the load development.

However, a 7mm 154gr at 2,900fps isn't "tossing nerf balls". Shot placement is most important consideration.

 

[gamestalker]

Been there and done that.

I couldn't get what I was trying to achieve, that being 3150's with 145 gr. bullets. I ended up moving to RL22 and IMR-7828, much better powders for those velocities I was wanting. RL22 seems to run a bit higher pressures IMO, but nothing that has ever given me problems, other than losing a couple loads from the brass life. There are some other good one's also, but I settled on those two cause they delivered great accuracy while getting me more realistic velocities.

GS